1. Field of the Invention
This invention generally relates to determining sequential location of limited range wireless communication devices arranged in an array so as to enable end-to-end communication for the array. Primary application is to electro-pneumatic braking systems for railroad trains wherein the invention relates, more particularly, to a linking process for determining the sequence in which the cars are attached to the train.
2. Description of the Prior Art
A linear array of short-range wireless nodes enables communications over a range far greater than the communication range of an individual node. A particular example of such a system is the wireless electro-pneumatic braking (EPBrake) system being introduced to the railroads by GE-Harris, Melbourne, Fla. This EPBrake system utilizes radio links to convey information up and down the train. Each car in the train has a radio of limited range, about five to ten cars, as compared to the length of a train which can be about 250 cars (11/2 to 2 miles in length). The key enabling technology for the deployment of the wireless network is the ability of the nodes to autonomously determine their sequential location and relay or forward messages to provide end-to-end communication in a timely manner. In particular for the EPBrake system, at the time of assembly of a train, the head-end unit (HEU) in the lead locomotive needs to ascertain the identities of the cars connected in the train, through a process termed the Linking Process. During the linking process the HEU also needs to ascertain the sequence in which the cars are connected to the train. This is referred to as "serialization".